disslocated toes

My Marran hen is at least 3 and she seems to have a recurring problem of disslocating her toes.

The first we know is when she is spotted stumbling and limping around the garden, this has happened 3 times. Each time I turn the toe back to the normal place, bandage it with sticky tape and about 6 weeks later it is healed. If the tape comes off any earlier the toe turns back round. (she doesn't seem in that much pain when I fix the toe and will sit still so i can pick her up and do it.)

Any ideas why this is happening, does she need more calcium or does she have some bone or joint illness? She lives with 7 other chickens and they all free range. I have checked everywhere for potential hazards but found nothing she could injure herself on, and the others are all fit and well.

The only thing I can think of is the perches in my coop are round, not square, could she be catching her toes when she flies up to roost?

I have no words of wisdom but; I have an Americauna that has been that way since I took her home. One of her outside toes turns out but she's never limped on it and has no problems getting around so I've just left her as is. I'm sure it was caused by some kind of deficiency when she was a chick but she was the only one out of 6 that it happened to.
Good luck with your hen!!